Process for obtaining the subtitles of kinematograph films



Dec. 5, 1949 KAGANSKY 2,490,442

PROCESS FOR OBTAINING THE SUBTITLES OF KINEMATOGRAPH FILMS Filed Jan.15, 1947 a) M M Patented Dec. 6, 1949 PROCESS FOR OBTAINING THESUBTITLES OF KINEMATOGRAPH FILMS Nachoum Kagansky, Paris, FranceApplication January 15, 1947, Serial No. 722,193 In France January 22,1946 1 Claim.

The invention relates to the process for obtaining the sub-titles ofkinematograph films which comprises forming on the film an acidproofresist (for example a layer of parafiln), eliminating the resist alongthe contour of the letters of the sub-titles by effecting an impressionby means of typographic characters, preferably in the hot state,dissolving the silver of the emulsion layer at the places which havebeen exposed by the impression, and finally eliminating the resist.

The invention relates more particularly to dissolving the silver andaims at obtaining absolute transparency of the sub-titles by anoperation of minimum duration.

In carrying out the above referred process, the silver is dissolved byplacing the emulsion in contact with a nitric acid solution and the filmis then Washed. However, experience shows that it is difiicult toeliminate completely the silver nitrate produced. This residual silvernitrate is decomposed by light and becomes yellow or black, so that thesub-titles, instead of being a pure white contrasting with the picturebackground, are yellowish, of faulty appearance and sometimes difiicultto read.

It would be possible to treat the silver with hydrochloric acid anddissolve the silver chloride in sodium thiosulfate, but the conversionof the silver into silver chloride is too slow to enable a practicalapplication of this process to be effected in a machine having an outputwhich is acceptable from an industrial standpoint.

The process following the invention permits to obviate thesedifficulties by successively subjecting the silver of the emulsion tothe action of a nitric acid solution, to the action of a hydrochloricacid solution, to washing with water, to fixing with sodium thiosulfateand finally to a final washing.

By operating in this manner the output of the machine is satisfactoryand the quality of the sub-titles is substantially improved.

The accompanying drawing shows, by Way of example, a diagrammaticarrangement for the application of the invention.

In this drawing, A designates the film to be provided with sub-titles,which has previously been coated with parafi'in or other resistsubstance, in which the sub-titles have been printed by means oftypographic characters, preferably in the hot state in order tofacilitate the expulsion of the paraffin. Said film passes with a speedof 5 metres per minute over guide rollers I, 2, 3, 4, 5,

6, l, 8 and cylinders 9, H! and l l, the cylinders 9 and Ill beingpartly immersed in a tank l2 containing a solution of fuming nitric acidat room temperature, and the cylinder H in a tank l3 containing a 60Baum hydrochloric acid solution. Free rollers l4, l5, placed in theloops of the film give it the requisite tension.

The thickness of the cylinders 9, I0 and H is equal to or slightlysmaller than the width of the film between perforations, and as theyrotate, said cylinders bring the reagents into contact with the emulsionface of the film. The nitric acid attacks the silver of the emulsion andthe silver nitrate dissolves in the nitric acid of the tank 12. Thenitrate which may remain adhering is then converted into chloride in thetank l3.

Jets of washing water are projected on to the loop of the film passinground the roller l5, as shown diagrammatically at [6. The film thenpasses into a sodium thiosulfate fixing bath, in which the residualsilver chloride is dissolved, then into a final bath of washing water.The sub-titles thus obtained are absolutely transparent.

Of course, the invention is not limited to the practical detailshereinbefore described which have only been given by way of example.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is:

A process for obtaining the sub-titles of kinematograph films, whichcomprises forming on the emulsion layer of the film an acid-proofresist, eliminating the resist along the contour of the letters of thesub-titles by an impression by means of typographic characters,successively treating the silver of the emulsion layer first with nitricacid and then with hydrochloric acid separately, washing, fixing withsodium thiosulfate, washing again, and finally eliminating the resist.

NACHOUM KAGANSKY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,649,621 Slocum Nov. 15, 19271,704,124 Fiedler Mar. 5, 1929 1,861,827 Titus June 7, 1932 2,051,603Hruska Aug. 18, 1936 2,152,306 Grebe Mar. 28, 1939

